(a)[1]
State the change, if any, in the number of neutrons in the nucleus of the sample when a $\beta^{-}$ particle is emitted.
(b)[3]
The number of $\beta^{-}$ particles passing a fixed point in the beam during $2.0$ minutes is $9.8 \times 10^{10}$. Calculate the current, in $\text{pA}$, produced by the beam of $\beta^{-}$ particles.
(c)[2]
Suggest why the $\beta^{-}$ particles are emitted with a range of kinetic energies.